Micro gas turbine power generators have recently attracted attention and found practical use as emergency private power generators or medium-and small-scale distributed power sources. Gas turbines have a structure simpler than that of other internal combustion engines, can be produced on a mass scale, are easy to maintain and inspect, and operate at a low NOx level.
Micro gas turbine power generators of the next generation typically employ a structure of a single-shaft regeneration cycle gas turbine to improve the total power generation efficiency.
Thus, in such power generators, a compressor, a turbine, and a generator are arranged on one shaft, combustion gases from a combustion chamber rotate the turbine, and then heat exchange is conducted in a heat exchanger with the air that passed the compressor. The power generators of this type decrease, even if to a small degree, the loss of combustion gas energy and have a thermal conversion efficiency equal to, or better than that of conventional power generators employing diesel engines.
With the single-shaft regeneration cycle gas turbine, low-NOx exhaust gases are obtained with lean-mixture combustion, and using plate fin heat exchanger makes it possible to increase the heat exchange efficiency to about 90%.
On the other hand, micro gas turbine power generators are required to endure a large number of start/stop cycles and also to have the improved operation start-up characteristic immediately after they are turned on and to supply immediately the necessary power. This requirement is obvious for emergency situations, but is also valid for applications of such power generators as distributed power sources.
Therefore, plate fin heat exchangers used for heat exchange between combustion gases and compressed air are required to demonstrate an excellent heat exchange efficiency and to retain the attained heat exchange efficiency, while maintaining endurance sufficient to withstand vary intense heat input, in particular non-uniform temperature distribution inside the fluid channels and extreme variations of thermal load.